21180349 has 4 divisors (see below), whose sum is σ = 21189564. Its totient is φ = 21171136.

The previous prime is 21180343. The next prime is 21180373. The reversal of 21180349 is 94308112.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 5522500 + 15657849 = 2350^2 + 3957^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21180349 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21180343) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1989 + ... + 6805.

It is an arithmetic number, because the mean of its divisors is an integer number (5297391).

Almost surely, 2^21180349 is an apocalyptic number.

It is an amenable number.

21180349 is a deficient number, since it is larger than the sum of its proper divisors (9215).

21180349 is an equidigital number, since it uses as much as digits as its factorization.

21180349 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9214.

The product of its (nonzero) digits is 1728, while the sum is 28.

The square root of 21180349 is about 4602.2113163131. The cubic root of 21180349 is about 276.6799598458.

The spelling of 21180349 in words is "twenty-one million, one hundred eighty thousand, three hundred forty-nine".